1972 280 SE WRD

[jim 56]

First thanks for the replies about my muffler.I called Timevalve and he is making my pipes. Very nice guy name is Mike. My next problem is that the car warms up terrible. Once warm it runs ok. So I did the split linkage right after I started it. When I add fuel there is no difference. When I add air the idle picks up and is a lot better. I am therefore assuming that it is running too rich. I'm not sure what I should do I have taken the air filter off and there is no difference. I think I have to remove the oval shims I think this sh0ould make it leaner. Is this correct?
Thanks in advance Jim

[Lorsar]

You've taken the small round air filter off of the fuel injection pump? If you put your finger over it while the car is cold, do you feel suction?  The suction should stop once the car warms up.  In my case, replacing the WRD thermostat resolved the issue.

[wwheeler]

Mike is a great guy and easy to deal with. I have spoken with him many times.

If it runs well when warm, the WRD is probably shutting off, but you can check with the small air filter off. Also want to observe at roughly what temp it shuts off at. Should be around 165*F or so. any lower, the engine isn't warm enough. Any higher, you risk it not ever shutting off.

Since there was no difference in cold running with the filter off, it is not clogged and is fine. Yes, removing oval shims will lean the mixture only when cold. Should not effect the warm running mixture. I say that, but I have had to slightly adjust the idle mix knob on the back of the pump slightly when changing oval shims. Shouldn't have to, but there it is.

Hopefully you have enough shims stacked up that you can get it close. FYI, these engines do run rich when cold. So it won't be perfect when cold. The goal is a good warm running mixture.

[jim 56]

Thanks I shall try taking some out today

[jim 56]

Took a couple of oval shims out a lot better
Thanks Jim

[bracurrie]

Mike is a great guy and easy to deal with. I have spoken with him many times.

I have one of his exhaust systems and other than it being a little louder than OEM and I am very happy. I did have the system welded after I had it for a while.

Should not effect the warm running mixture. I say that, but I have had to slightly adjust the idle mix knob on the back of the pump slightly when changing oval shims. Shouldn't have to, but there it is.

Should the impact of the WRD be non-existent when the engine gets over 165 F? Or are you adjusting for cold running?
Just thinking logically, which is dangerous , but if the thermostat for the WRD isn't working properly couldn't that be why you have to adjust after taking out or adding shims?
Brad

[wwheeler]

The WRD thermostat is a wax and expands as it gets hot. It is always acting against a spring. Not sure if the wax slowly degrades and loses force per rise in temperature over time. Maybe.

Yes, the WRD is only effective until it reaches the shut off point. After that, there is a stop inside the IP that limits any further leaning of the mixture. The WRD bulb still expands with rising temperature, but once the pump hits the mechanical stop, it leans no more. The force of the expanding wax fights the spring below it. Eventually the spring force balances the force of the expanding wax and it comes to equilibrium.   

[jim 56]

So if I am understanding this right once car is warm WRD is out of the equation and that is what the lean/rich setting is. You can make car richer or leaner by adding or subtracting oval shims. But that is the baseline now you work off of that by turning flower screw on IP to get what you need.

[wwheeler]

The "flower screw" on the IP will adjust the fuel mixture at idle cold or hot. But best to reserve that adjustment when the engine is warm. The air screw also adjusts cold or warm. But again, use that only when the engine is warm. The oval shims are for exclusive use to adjust the cold running mixture ONCE the warm running mixtures are set. So in other words, I would adjust the warm running mixture they way you want it, then worry about the cold running mixture by changing oval shims. The cold running is less important because it is short term. The main focus is warm running.
 

[jim 56]

got it thank you